There's no such thing as too much of a good thing, as this drool-inducing, photo-heavy cookbook proves. Former pastry chef Klivans (Potpies ; Big Fat Cookies ) turns her attention to the most decadent of desserts, the chocolate cake, finding 50 different approaches. Klivans orients her readers with a narrative about chocolate production, tips for choosing and using chocolate, and basic tips about ingredient and technique in baking, such as beating egg whites. The remainder of the book is organized by cake type (quick and easy; layer cakes; party cakes), and the recipes run the gamut from a basic chocolate-chip loaf to her chocolate yule log and chocolate-apricot pudding cake with chocolate toffee sauce. Some, like her pavlova with chocolate-covered strawberries, and her trifle-like deep-dish white chocolate peaches and cream cake are not technically cakes, but who's counting? Klivans is nothing if not inventive—a basic devil's food recipe serves as a staple for seven other variants. With deft instructions and highly detailed, clearly written recipes, she guides even the least confident baker to a cocoa-dusted kitchen and full-on chocolate ecstasy. Photos. (Apr.)